Efficient and selective carbon-hydrogen activation by a tris(pyrazolylborate)rhodium complex

Ghosh, C.; Graham, W. A. G.

doi:10.1021/ja00249a048

Cited by 148 publications

(65 citation statements)

References 3 publications

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“…O rganometallic complexes of the cyclopentadienyl (Cp) and trispyrazolylborate (Tp) type have been shown to activate a variety of COH bonds in alkanes and arenes (1)(2)(3)(4)(5)(6)(7)(8)(9). However, studies on the activation of alkanes and arenes containing reactive functional groups have received far less attention in the literature.…”

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confidence: 99%

The activation of alkyl cyanides using a rhodiumtrispyrazolylborate complex

Vetter

Rieth

Jones

2007

Proc. Natl. Acad. Sci. U.S.A.

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O rganometallic complexes of the cyclopentadienyl (Cp) and trispyrazolylborate (Tp) type have been shown to activate a variety of COH bonds in alkanes and arenes (1-9). However, studies on the activation of alkanes and arenes containing reactive functional groups have received far less attention in the literature. Hartwig and coworkers (10-12) have been successful in the hydroborylation of mono-and disubstituted arenes using transition metal catalysts. The borylation of the arene ring is believed to occur after oxidative addition of the ring COH bond without interference of reaction with the functional group. Smith (13,14) has even shown that haloarenes can be borylated and functionalized without affecting the carbon-halogen bond. Although numerous examples are presented for the functionalization of substituted arenes (15), the functionalization of alkanes containing reactive functional groups is somewhat restricted, perhaps because some of the functional groups on the alkanes are more reactive toward the catalysts and do not allow for COH activation. In addition, some functional groups (e.g., OH) are known to make the adjacent COH bonds more reactive in alkanes (16).We recently reported the activation of 1-, 2-, and 3-chloropentanes using a trispyrazolylborate rhodium complex (17). It was determined that the [TpЈRh(L)] fragment did not oxidatively cleave the COCl bond of the chloroalkane, as would have been expected given the relative bond strengths of COH (Ϸ100 kcal) vs. COCl (80 kcal) bonds (18) and the literature precedence that exists for the oxidative addition of COCl bonds to Rh(I) and Ir(I) metal systems (15,19). Surprisingly, the [TpЈRh(L)] fragment reacted exclusively with the terminal COH bonds of the alkane to give the substituted haloalkyl hydride complex. Here, we extend the investigation of the activation of hydrocarbon COH bonds to include substrates containing the nitrile functional group (OC'N).The COH bond activation of acetonitrile has been documented in the past. Teuben and coworkers (20) have reported the COH activation of acetonitrile via a -bond metathesis using Cp* 2 LnCH(SiMe 3 ) 2 . Jesson and coworkers (21) have also documented the formation of the cyanomethyl hydride as a result of activation of acetonitrile using (dmpe) 2 M(Np)H (M ϭ Fe, Ru; Np ϭ 2-naphthyl). The scission of the COCN bond of acetonitrile has also been reported by Parkin and coworkers (22), Brookhart and coworkers (23, 24), Nakazawa et al. (25), and Jones and coworkers (26). Of particular interest is the work by Brookhart using a similar Cp*Rh(PMe 3 ) system (23), which is known to undergo COH bond activation in the presence of alkanes and arenes (3,27). However, in the presence of nitriles and triphenylsilane, the complex promotes the cleavage of the COCN bond.To demonstrate the diversity of nitrile reactivity with low valent metals, our group has also investigated the reactions of aromatic, allylic, and alkyl nitriles using [(dippe)NiH] 2 (28-30). In these studies, 2 coordination of the CN bond to the Ni metal cent...

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confidence: 99%

The activation of alkyl cyanides using a rhodiumtrispyrazolylborate complex

Vetter

Rieth

Jones

2007

Proc. Natl. Acad. Sci. U.S.A.

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“…366 nm irradiation of the yellow complex 1 led to the colorless phenyl hydride product in good yield. The quantum yield was determined to be 1.0 AE 0.3, which is higher than for many other organometallic photoprecursors [2][3][4][5][6] …”

Section: Hydrocarbon Activation By [Tp 0 Rh(cnr)]mentioning

confidence: 68%

“…The 16-electron fragment that apparently forms is rapidly trapped by the solvent to give 2-d 6 . The true mechanism, however, is one in which the benzene is displaced.…”

Section: Hydrocarbon Activation By [Tp 0 Rh(cnr)]mentioning

confidence: 99%

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The Effects of Ancillary Ligands on Metal–Carbon Bond Strengths as Determined by C–H Activation

Jones

2015

Topics in Organometallic Chemistry

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The activation of C-H bonds by oxidative addition in about 30 different substrates has been examined with three closely related metal species, [Tp 0 RhL], where L ¼ CNneopentyl, PMe 3 , and P(OMe) 3 . Kinetic studies of the reductive elimination of R-H provided data to ascertain the relative metal-carbon bond strengths for a wide range of compounds. Trends in these bond strengths reveal that there are two classes of C-H substrates: parent hydrocarbons and substituted methanes. DFT calculations are used to support the observed trends, and some generalizations are made by comparison to other metal systems.

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“…1 Transition metal complexes containing N-heterocycles are gaining significance because of their relevance to metalloproteins and catalytic activity. [2][3][4][5][6][7][8] A variety of transition metal complexes containing multidentate N-heterocycles has been reported from these laboratories. 9-14 1,3-bis(benzimidazolyl) benzene forms cyclometallated complexes with palladium and rhodium.…”

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confidence: 99%